It has been shown in our laboratory that glucocorticoids suppress ornithine decarboxylase activity in hairless mouse skin. We would like to continue with this work to find out the time relationships between the glucocorticosteroid application and the inhibition of ornithine decarboxylase activity. We also want to see if glucocorticoids inhibit the DNA synthesis stimulation by polyamines applied topically to the surface of the skin and to look at ornithine decarboxylase activity in proliferative models in hairless mouse skin such as essential fatty acid deficient mice and Retin-A stimulated mice. We want to pursue the effects of UVA and anthracene on animal skin and try to develop a preparation which can be used eventually in the treatment of psoriatic plaques with ultraviolet A and anthracene. We are also investigating a new technique for quantitating the effects of sunscreens on blocking out UVA and UVB. We are utilizing the hairless mouse DNA synthesis model for this purpose and have already shown that this is a highly reliable and feasible model for testing the effectiveness of sunscreens.